Ink jet recording apparatuses typically employ recording heads that are designed to jet ink droplets out of nozzle openings. The jetting is caused by applying pressure to ink chambers using piezoelectric vibration elements or heating elements. In these apparatuses, measures must be taken to prevent the drying of the ink in the vicinity of the nozzle openings as well as impairment of the print quality due to dirt and dust deposits in the vicinity of the nozzles.
As one such measure, the recording head is moved to a capping device set in the standby position every time the print operation lasts a predetermined time, e.g., 20 seconds, so that ink droplets are jetted out of the nozzle openings into the capping device.
The ink discharged to the capping device this way is sucked into a discharge ink tank every time a predetermined amount of ink has been discharged by driving a pump connected to the capping device.
There are basically two types of systems for driving the ink discharge pump. One uses power from a dedicated drive motor, and the other uses the force of the print mechanism. By requiring a separate motor, the former system has the disadvantage of a larger overall system and a higher cost. On the other hand, the latter system can get pump driving power from the print mechanism drive source by employing a simple transmission mechanism, and therefore the latter system has a simpler structure that is highly reliable and less costly. However, the latter system requires that the print mechanism drive motor be reverse-driven to switch the print mode. In this situation, the shortcoming of banding can occur in printouts due to sheet forwarding errors if the transmission mechanism backlashes.
As a solution to these problems, the backlashes could be eliminated by inserting an elastic member, such as a spring, into the transmission mechanism. However, this approach is expensive.